[BlueOnyx:06218] Re: Increasing disk capacity using RAID rebuilds

[Chris Gebhardt - VIRTBIZ Internet]

Richard Morgan wrote:
> First of all, Happy New Year - it sounds like 2011 is going to be an 
> exciting year for BO/BX.

Indeed!

> Is there any way to increase the disks in use on a live server without a 
> complete rebuild and transferring all the sites?

You can resize partitions, and it would be a multi-step process, for 
sure.  But it can be done.

> I am hoping it would be possible to do something like swap secondary 
> RAID disks to the larger capacity, let it rebuild, move this to primary, 
> put another large disk is as secondary and rebuild again.
>  
> I've tried this on a test server, but I cannot find how to get linux to 
> see the larger disks or the extra capacity beyond the size of the 
> original disk size.  I guess this is possible, but I've missed an 
> important step somewhere.

No, that won't work since the Linux raid will always create a mirror.

> Any ideas or pointers would be greatly appreciated.

I might suggest a 3 step process.
1. Attach a spare drive (ie: 3rd drive, not in the RAID) and move your 
/home partition to it.
2. Resize the old /home partition on the RAID by replacing one drive at 
a time and letting them sync up.  Then destroy what was the /home 
partition and create a new one in its place that takes up the maximum 
amount of space on the new disks.
3. Move /home back to the RAID.

I've done a similar process many times to do a drive upgrade.  Or in 
some cases moving /home (where all the site, user, and MySQL data is 
stored) to another drive or array entirely.  I don't know that I've ever 
done it using the steps I outlined above, but don't see why it wouldn't 
work.   It will mean some downtime with reboots and so forth, but if 
you're willing to put up with it that could be a way to go.

-- 
Chris Gebhardt
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